Power transmission in jaw crushers



Sept. 9, 1952 K. GAULDIE POWER TRANSMISSION IN JAW CRUSHERS 5 Sheets-Sheet 1 Filed April 9, 1948 IN V EN TOR. Ae'nneih GauYdie "214. 5 WMQL ATTORNEY FIG. 5

FIG. I

Sept. 9, 1952 K. GAULDIE 2,609,994

POWER TRANSMISSION IN JAW CRUSHERS Filed April 9. 1948 5 Sheets-Sheet 2 FIGS INVEN J8 Aenneih 6a is 5 BY 6 6% 6? A TTORNEY P 1952 K. GAULDIE 1 2,609,994 9 POWER TRANSMISSION IN JAW CRUSHERS Filed April 9 1948 5 Sheets-Sheet 3 IN VEN TOR. Kenneth Gauldie BY atm I A TTORNEY K. GAULDIE POWER TRANSMISSION. IN JAW CRUSHERS 5 Sheets-Sheet 4 FIGQ Sept. 9, 1952 Filed April 9, 1948 ATTORNEY INVENTOR. AenneZh @auldz'e BY fim fl Sept. 9, 1952 K. GAULDIE 2,609,994

POWER TRANSMISSION IN JAW CRUSHERS Filed April 9, 1948 5 Sheets-Sheet 5 IN VEN TOR.

k'ennef'il auldz'e BY Q0 8 19 7M &

ATTORNEY Patented Sept. 9, 1952 UNITED STATES PATENT OFFICE rowan TRANSMISSION IN JAW onosnnas Kenneth Gauldie, Toronto, Ontario, Canada Application April 9, 1948, Serial No. 20,140 In Great Britain April 27, 1941 Claims.

i The present inventionrelates to jaw crushers and particularly .to improvements in the manner and means of power transmission to the oscillatcrushing chamber between the jaws only during the return stroke of the swing jaw. During such return Stroke, the whole charge moves downwards as the swing jaw moves backward and (provided that time is available for descent under gravity) a wedge of crushed material can emerge of which the greatestwidth is equal to the distance apart of the jaw tips at open setting.

During each complete oscillation of the jaw of a conventional crusher, the time available for the descent under gravity, from rest, of the crushed material is one half of the period of the oscillation. The distance through which material can fall from rest, under gravity, varies as the square of the time available for descent and therefore decreases rapidly with decrease in available time. If the speed of a jaw crusher is progressively increased from zero there will, at first, be suflicient time available during each return stroke for the whole of the potentially-emergent wedge .of crushed material to fall clear. of the jaws. 'Under such conditions, the same volume of material will emerge each revolution and the capacity of the crusher will be proportional to its speed. As the frequency of oscillation of the jaw is "increased, a critical speed willbe reached such that the distance through which crushed material can fall from rest during the return stroke is just decreases as the square of the time occupied in a return stroke; that is, the height of eachemergent wedge varies inversely as the square of the frequencyof oscillation. The number of emergent wedges varies, however, directly as the frequency.

2 a. It follows therefore that the capacity of acrusher operating above its critical speed tends to be inversely proportional to its speed.

A primary object of my invention is toprovide mechanism whereby the proportion of the period of a complete oscillation of the jaw of a crusher which available for the falling of the crushed material by gravity is increased with consequent increase in capacity or potential capacity of the crushenfl Further objects and advantages of my invention will become apparent from a consideration of the following detailed description of embodiments ofiny invention taken together with the accompanying drawings in which Figs. 1 and2 are diagrammatic showings of conventional jaw crushers for the purposes of explaining the principles of my invention; Fig. 3 is adiagrammatic showing of an embodiment of my invention; Fig. 4 is a graph; Fig. 5 is a diagrammatic showing of another embodiment of my invention; Fig. 6 is a sectional .view of a valve arrangement useful in the modification of Fig. 3; Fig. '7 is a valve arrangement useful in. the modification of Fig. 5; Fig. 3 is vasectional View illustratingcertain details; Fig. 9 is a further modification of my invention; and Figs. 10,11 and 12 are graphs useful in the explanation of the modification of Fig. 9.

Referring to the drawings, Fig. 1 is a diagrammatic showing of the crushing elements of a conventional jaw crusher in which the movable jaw l is caused to oscillate about the shaft 2 and to crush the material which descends between it andthe fixed plate 3. The jaw is shown in full lines at the forward end of the crushing stroke and in dotted lines at the rearwardend thereof. It will be evident that a wedge ofcrushed mate rial of which the maximum breadth is equal to the distance apart of the jaw tips at open setting andof which the height is, represented by the letter h in the figure, may fall out, during the back Swing of the swing jaw provided that time is available for descent under gravity through such distance.

Fig. 2 is a similarconventional showing of a crusher in which the'swing jaw has a curved face andin which the included angle a. between the jaw surfaces at outlet is relatively low. By comparison with Fig. 1 this figure illustrates the influence of the included outlet angle on the height h of the potentially-emergent wedge and on the capacity of a crusher.

It has previously been indicated that the capacity of a crusher is proportional to its speed until a .critical speed has been reached after 3 which this capacity declines as the speed is further increased. In the graph shown in Fig. 4 in which speed or R. P. M. is the abscissa and capacity is the ordinate, the proportionality of capacity to speed up to the critical point at C is indicated by the straight line a passing through the origin. Up to the critical speed, it is the height h. of the potentially-emergent wedge ,whichdetermines the volume of crushed material which is discharged during every return stroke of the swing jaw. At the critical speed, the time available during the return stroke is exactly sufficient for the fall of material under gravity through the height 71.. Beyond the critical speed, thedistance through which material can fall undergravity in pipe H5 is equipped with a valve 11.

to. the ram cylinder 8. and to,the sump l9.

- the ram 4 is forced forward on the downstroke of the time of the return stroke decreases rapidly: as-- speed is increased; and the falling line b-'---indicates the manner in which, for that reasonthe capacity of a crusher tends to decline at speeds above the critical. f v

It will be apparent'therefore that the, maximum capacity of a crusher depends on its critical speed.

. Any measure which would have the effect of in- .creasingthe critical speed (as from C .to'iD) has consequently the effect of correspondingly increasing the maximum capacity of the crusher. Any driving arrangement for the movablejaw which increases the proportion of the period of crusher.

The effect on the capacity of a crusherof an ..increase inthe. critical speed is illustrated by comparison of the lines b andk whereby it will be evident that the capacity of a crusher at. any

speedy beyondxthecritical is increased if the critical speed is raised. j Forexample at the speed g the capacity of the crusher is increased from c to f by the raising of 'thecritical speed from c to d. It willalso be apparentfrom the diagram that the same capacity e will be attained at a higher speed in if the critical speed'is increased and that. the work done per stroke and the forces transmitted through the structure ofthe' crusher may be reduced accordingly.

It will also be evident that if the capacity 1 obtainable at .the speed 9 from a machine operating in accordance with thecurve 7c is greater thanis desired, .thatcapacity may be reduced by corresponding reduction in the jaw movement and .that the size-uniformity of the product may be improved.

The lengthening of the proportion of the period of "a complete oscillation .whichis availablefor "outfall of material, permits therefore by com- 7 parison with .jaw crushers of conventional design,

of" greater capacity, or higher speed and lighter "construction, or greater uniformity. of product, or

acombination of these advantages.

Fig. 3 shows an emboliment of my invention in which the forward crushing force, developed as a "hydraulic pressure by the plunger 9, is applied to the swing ,jaw i, by means of .a ram 4 acting "through an intermediate rocker 5. The swing jaw is retracted during its return strokebyaspring 5; but its'movementsare controlled by movements of the plunger e. And when the plunger reaches "the top of its stroke the ram coniesquietly to rest'against the 'adjustable'stop- 1 in the base of the hydraulic cylinder. 'The. power-driven plunger 8 operating in hydraulic cylinder in is driven from the shaft ii, attwice the speed of oscillation desired forthe jaw l A suitable pipe l2 delivers liquid from the bottom of'cylinder I0- the plunger 9 to deliver a crushing stroke to the jawl and is then retracted to its position against Y the stop 7 bythe spring 6 on the upstroke of the plunger 9. On the next downstroke of the plunger 3 and during its subsequent return stroke,

the valved? is open and the plunger 9 is idling, the jaw-i being held in its open position by the tension of the spring 6. It is apparent that the period of time available for outfall of crushed material from the crusher is three-quartersof the completeperiod of oscillation of the j aw. =It'wi1l also be apparent that,as the proportion of the time of each oscillation of the jaw during which discharge may take place has been increased, the

' critical speed of a crusher of which the jaw move- 1 ment and outlet angle are given, has increased an oscillation during which the swing jaw is being retracted, causes the critical speed to be raised U and hence increases themaXimum capacity of the and .Jthat, by comparison with a conventional crushenthe capacity of the crusher hasbeencorrespondingly increased.

.Fig. 6 of the drawing showsa suitable'form of commutating valve ii. The valve is biased 'to open position by a spring 29 and is moved against the pressure of the spring by a suitable "cam .23 driven athalf the speed of t-he shaft *HQ'The .cam is appropriately shaped'to bring the valve [1 nearly intocontact' with its seat when the plunger 9 is at the commencement of an active stroke and to permit the valve to be open under the influence of its springduringi one halfof the cams'revolution. i

The relief or safety valve l8 (Fig. 3)j'inthe pipe 15' opensiif the pressure in'the hydraulic system exceeds. a predetermined-value andispro vided to prevent undue strain in thacru'sher structure as a result" of 'tramp' steel or other uncrusha'ble material becomingcaught between the jaws. The valve 5 in pipe I3 is am'anually operated valve which may be closed gradually to facilitate the startof a crusheragainst afull chamber, q

In the diagrammatic arrangement, 3, two separate swing jaws" are indicated, each'with its separate crushing chamber and separate hydraulic'system comprisinga ram'and'plunger. 'The two plungers 9 and 9' are operated from the same crankshaft II by cranks degrees apartybut apart from this mechanical linkage, the crushing system illustrated in this'figure comprises two independent units, the swing jaws or which operatealternately. I

The two crushing units are shown .in the.dia-

gram as in series. Such an arrangement would be suitable if a very large reduction-ratio were required from a single installation. Normally, howeventhe swing jaws would be mounted sideby-side in'the same crushing chamber and on the same shaftZ and would operate in parallel.

Because of the alternate operation of two. halfwidth swing jaws, the work done per 'j'aw (by comparison with a conventional crusher) is halved, the forces transmitted through .the' frame are reduced and the structure may be lightened accordingly.

I have also illustrated in'Fig. 3 pipe connections indicated at 22 whereby fluid leakage past the plungers 4 and 9 is returned tothe sump I9. If no leakage occurred past the rams and plungers or elsewhere, each ram and its associated swing jawwould oscillate between definite limits. Leakage cannot however be avoided andas a result of leakage the jaws'would tend to oscillate between receding limits. For that reason a jaw comes to rest on its stop I a little before the plunger 9 has reached the end of its reduction strokeand the continued slight movement of the plunger to the end of its stroke draws liquid from the sump l9 through the semi-automatic valve l1. 1 Irrespective of the occurrence of leakage, the hydraulic system therefore contains. a definite volume of liquid when the plunger 9 is at the beginning of an active crushing stroke.

'In'Fig. I have shown a two-jaw crusher arranged in the manner of Fig. 3 and which: differs therefrom in that a single plunger 9 is provided foroperating the pair of rams 4. The same references are applied to the same parts as in Fig. 3. Mechanism is provided which places the plunger chamber in alternate communication with the two rams 4. The pipe 12 leading from the plung er cylinder III to supply the rams has a pair of branches 23 and 24 one leading to each of the ramcylinders 8 of one of the crusher jaws. The branches 23 and 24 are provided with valves diagrammatically shown in Fig. 5. In Fig. '7 I have shown a valve mechanism suitable for controlling the delivery of fluid through the pipes 23 and 24. A single valve 25 cooperates with a valve seat in the conduit 23 when in an upper position and also cooperates with a valve seat in the conduit'24 when in its lower position. The valve 25 is spring biased to move in an upward direction and is actuated against thespring by a cam 26. The cam 26 is driven in timed relation with the plunger 9 whereby for one complete stroke of the plunger 9, the inlet to conduit 24 is closed (the position illustrated) andthe lower ram'4 is idle, held against its stop 1 by its return spring 6. During this stroke, the inlet to the conduit 22 andthe upper ram cylinder 8 is open. ,Onthe succeeding stroke of the plunger 9,the valve 25 is seated on its upper seat closing the inlet. to conduit 23- and opening the inletto conduit 24 whereby. the lower ram 4 is actuated and the upper ram 5 is held idle against its stop l. Makeup for leakage of fluid past the rams 4, and the plunger 9 is provided for by-the checkvalve 21 in a pipe leading from the sump l9. In the same manner as described in the modification of Fig. 3, if due to leakage one of the rams 4 is returned against its stop by its spring before the completion of the upstroke of the plunger 9, the continued movement of the plunger 9 to the endof its stroke causes the check valve 21 to open permitting liquid to bedrawn in from the sump 19. While I have shown in Fig. 7 a single .valve for the control of the passages 23 and 24, it is apparent that each of the passages may be separately controlledbya valve actuated by a separate cam. In the modification of Fig. 5, I have shown other pipes leading from the bottom of .theplunger chamber ID to the sump ls including a manually operated starting valve 16 and an automatic pressure relief valve l8 for the same purposelas the similarly numbered valves described in connection with Fig. 3. v

In Fig. 9 I haveshown a further embodiment of my invention in which hydraulic mechanism isillustrated whereby a quick forward stroke and aldelayed return stroke is obtained without the use of control valves between the driving plunger chamber and the ram as described in the-em bodimen ts of Figs; 3 and 5. Reference character 30 represents a plunger operating in hydraulic cylinder 3|, and 32 illustrates another plunger operating in hydraulic cylinder 33. The bottom of cylinder 3| is in communication with the bottom of cylinder 33 and the pipe l2 connects the ram cylinder 8 to both these plungercylinders without intervening valves. Themove ment of the ram 4 is thus the resultantof the combined action of the two plungers 30 and 32. The plunger 30 is connected to be driven by a crankfrom the shaft 35"and the plunger 32 is connected by a crank to be driven from the shaft 36. The shaft 36 as diagrammatically shownis arranged to be driven at half the "speed of the shaft 35. reciprocate at twice the speed ofthe plunger32 and by their conjoint action the two plungers provide a quick forward stroke of the ram 4 and a much longer return stroke.

The operation of the mechanism of Fig. 9 will be understood with reference to the diagram Fig. 10. In that diagram the displacement of the slow-speed plunger 32 is represented by the harmonic curve a and the displacement of thehigh.

speed'plunger 30 by the harmonic curve 11.

Since both plungers are in communication with each other and with the ram it follows that the displacement of the latter is the resultant of the displacements of the two plungers.

. The full line curve 0, Fig. 10, which represents the displacement of the ram, results from the compounding of the two simpler periodic curves a and b. It will be noted that the period t of a complete cycle of jaw movement is equal to the period of the slow-speed plunger.

The condition when the ram 4 is momentarily atirleston itsistop I is represented by the point d on the curve. In the interval between the points (1 and e the ram is forced forward in its active, or crushing stroke, through its full amplitude it. During the remainder of the period it, (between points. e and k on the curve) the ram and the swing jaw are retracted from their extreme for ward positions and crushed material is, consequently, free to emerge from the crushing 'chamber during the corresponding interval... 1

As is evident by inspection, the time involved inthe return stroke of ram and swingjaw is very considerably more than half the complete period of oscillation of the jaw. J l

The secondary forward movement of the ram and swing jaw which occurs between points 1 and g on the curve does not necessarily affect the capacity of the crusher in any marked degree. It does, however, affect the manner of descent of material in the upper portion of the crusher chamber, and it may or may not be a desirable feature according to the conditions of operation of the crusher. As indicated in Figs. 11 and 12 this secondary movement may i be completely eliminated by adjustment of the relative displacements of the two plungers and their. phase relationships. 7

Under the conditions of relative displacement and phase relationship indicated in Fig. 11 the rapid crushing stroke between points at and e is followed by a rapid retraction of the ram between points e and f on the curve. At the end of this period the ram has almost completed its return stroke but has not quite contacted its stop. The remainder of the period from f to k is available for the slow and gradualap- The plunger 30 is thus caused to preach; of the ram, into; contact. with: its iston That is, the object attained by the plunger relationships indicated'in Fig. 11,,isthe minimization of ;an,y--shoc,k-;-which may occur when the ram contacts its stop. a

, Fig.,12;indicates how, by other choice in. displacement and phase.-;relationships of the two plungers, a relatively uniform velocityofj-ram and swing jaw during the return stroke-maybe attained;

It will, be'understood that the general; principles which have been explained with reference to two plungers apply with respect to the come pounding, of-the'motions of a greaternumber of'plungers and'thatthree or more .plungers runninggat diiierent speeds maybe employed in conjunctionwith a single ramp In themodification of;Fig-: 9, checkvalve-zl, provides for makeup-fluid to; compensate for leakage. in the same manner as has been de' scribed inconneetion with,Fig.5.-

In Figs. 3, and 9, I have illustrated mor or less diagrammatically a stop (I against which the ram l comes to rest on its return stroke. In Fig. 8 I have-shown stop mechanism which pro vides ,foritheabsorption of shock between the ram and its adjustable stop and ,whichalso provides for the automatic release of uncrushables.

This: mechanism comprisesa shaft 52 mounted for longitudinal reciprocationin the casing and having a head 53' of substantial, area ,to be en.- gaged by the end of-the ram 4. The shaft 52 has apiston 54 mounted thereon; for adjustment therealong and-which operates in the cylinder 55. Piston 514, is backed by a compression spring 55 which-is" ofsuificient strengthto. maintain the piston 54 inthe position shown, against the pressure exerted thereon through the ram 4 by the. return spring ,5. The cylinder 55 is provided with ,an inlet port 51 and an. outlet port 58. The inletaport 51 is connected by a pipe to the outlet portof the relief valve l8, and the outlet port 58 is connected by a pipecto the sump. :In; normal operation thev layer of oil between the ram .4 and the head: 53 together with the spring. 56-act to cushion the shock of contact of the ram with its stop at the end of the stroke of the former. If, however, uncrushable material enters between the jaws of the crusher, fluid in the hydraulic systemis expelled on the crushing stroke of th plungers, through the relief valve 18 and'thence through the port 5T'into the cylinder 55. The pressure of fluid in the cylinder 55 drives the piston 5% against its spring till the outlet port 58-is uncovered, whereby the liquid discharges tothe sump. As the stop 53 moves back 'with the piston 54 when the relief valve comes into operation, theswing-jaw I is free to move back under the influence of its retracting spring until the obstruction is dischargedfrom the crusher. The relief valve then closesand the stop moves back to its previous setting at a slow rate dependent on the rate at which liquid caught behind.- the piston can escape past it 'to the output port. The mechanism just described thus provides for the absorption of shock-at the moment of contact-between the ,ram and its stop andalso provides for the automatic release of uncrushables and for subsequent, automatic resetting of the swing jaw.

What I claim a's new and desire to secure-by Letters Patent'of the United States is 1. In a crusherhaving a reciprocatable jaw, a hydraulic systemfor operatingthe jaw to produce crushing strokes thereof including a ram cylinder, a ramsin; the cylinder actingonsaid jaw, and a hydraulic power-transmitting liquid engaging said ram-,- and meansforzimparting -,a return stroke to the jaw after completion of each crushingstroke, a power-driven, oscillating, primary member engaging said liquid to produce pressure impulses therein-and a secondary memher having a periodic. movement the frequency of which ishalf that'of the pirmary member, said secondary member engaging said liquid to transmit conjointlyawith the primary member, pressure impulses to. the ram. to forcethe jaw forward in crushing strokes eachsextending from the extreme backward limit to theextreme forward limitof movement of the jaw, saidcrushing strokes having a frequency equal to that of said secondary member, and the duration of each said crushing stroke being less than half the period of one cycle of movement of said secondary memb'en. I

2; In a, crusherhaving areciprocatable jaw, a hydraulic system for operating the jaw to'produce crushing strokes thereof including a ram cylinder, a ram in the cylinder acting on said jaw, means forming a passage leading to said cylinder, and 'a hydraulic power-transmitting liquid filling said passage and engaging saidram, and means for imparting a return stroke to-the jaw after completion of each crushing stroke, .a power-driven oscillating member engaging said liquid to produce impulses of hydraulic pressure therein, means forming a space hydraulically disconnected from the ramcylinder,-and-a commutating valve mechanism in said passage having a port leading to the ram cylinder and a second port leading to said space, said mechanism including means for opening said first port and closing said second port during each alternate complete oscillation of said member to transmit the impulse produced by each said alternate oscillation to the ram cylinder, said latter impulse actuating the ram-to impart-a crushing stroke to the jaw, andfor closing-said first port and opening said 'second'port during each intervening oseillation'of saidmember to prevent transmission of the impulse produced by each said intervening'oscillation to the ram cylinder.

3. A jaw crusher, comprising a reciprocatable jaw, a hydraulic system foroperating said jaw including a ram cylinder; a second cylinder, means forming a passageconnecting said cylinders, and a hydraulic liquid filling said passage, a ram in the ramcylinder'acting on the jaw, a power-driven oscillating member in the second cylinder, said liquid engaging said ram and oscillating member, said oscillating member having a substantially uniform frequency of oscillation to produce hydraulic pressure impulses of equivalent frequency in said liquid, means for preventing transmission of each'alternate one of said impulses to said ram cylinder comprising means forming aspace hydraulically disconnected from said ram cylinder, a commutating valve mechanism in said passage having a'port communicating with said ram cylinder and a second port communicating with said space, said mechanism including means for closing saidflrst port and opening said second port duringeach alternate oscillating cycle of said member to permitpasr' sage of liquid to said space and for, openingrsaid first port and closing said second port, during each'other oscillating cycle of, said'member to cause transmission of a respective impulse to the ram cylinder, said transmitted impulse being operative to actuate-the ram to apply a crushing stroke to the jaw, and means for imparting a return stroke to the jaw at the end of each crushing stroke, said transmitted impulses thereby having a frequency half that of said member, and the duration of each said crushing stroke being thereby less than half the period of one cycle of oscillation of the jaw.

4. A jaw crusher comprising a pair of reciprocatable jaws, apair of ram cylinders, a ram in each cylinder acting on one of said jaws, a third cylinder, a power-driven oscillating memher in said third cylinder, means forming a separate passage leading to each of said ram cylinders, means forming a passage connecting said third cylinder with both said first passages, a hydraulic liquid filling said passages and engaging said rams and member, said oscillating member having a substantially uniform frequency of oscillation to produce hydraulic pressure impulses of equivalent frequency in said liquid, a commutating valve mechanism at the junctures of said second passage with said first passages and controlling communication therebetween, said mechanism being operative to place said second passage in alternate communication with one only of said first passages during each oscillating cycle of said member to cause transmission of each alternate one of said impulses to a respective ram cylinder, each transmitted impulse being operative to actuate the respective ram to apply a crushing stroke to the respective jaw, and means for imparting a return strok to each jaw at the end of each crushing stroke, the impulses transmitted to each ram thereby having a frequency half that of said member, and the duration of each said crushing stroke being thereby less than half the period of one cycle of oscillation of each jaw.

5. Ina crusher having a reciprocatable jaw, a hydraulic system for operating the jaw to producecrushing strokes thereof including a ram cylinder, a ram in the cylinder acting on. said jaw; means forming a passage leading to said cylinder, and a hydraulic power-transmitting liquid filling said passage and engaging said ram, and means for imparting a return stroke to the jawjfafter completion of each crushing stroke, a pair of power-driven, oscillating members each engaging said liquid to produce pressure impulses therein, the frequency of one of said members being double that of the other member, said member of lower frequency acting to displace liquid into said ram cylinder while said member of higher frequency is also displacing liquid into said" ram cylinder.

KENNETH GAULDIE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

